DFT Investigation On The Confined Ionic Liquids

In recent years,the application of confined ionic liquids in catalytic reactions and gas capture has attracted much attention,and its excellent characteristics have shown good application prospects.However,currently,there are few studies on confined ionic liquids by calculation,and most of them focus on the molecular dynamics of confined ionic liquids.In this paper,the structure and properties of ionic liquids and confined ionic liquids and their adsorption capacity for CO₂ were studied in depth through quantum chemical simulation methods.The calculation uses the density functional theory?DFT?method,using the Gaussian 09 program and other quantitative analysis software.?1?Using the density functional theory?DFT?method,using nano-SiO₂ as the carrier,The structure-property study of[EMIM][Br],[EMIM][Cl],[EMIM][CH3COO]and[EMIM][PF₆]was carried out.The changes in the structure,charge value and interaction force between the ionic liquid and the confined state,as well as the changes in the structure,charge value and interaction energy of the anion and cation at different positions in the carrier are analyzed.Some important conclusions are obtained:?1?By changing the loading position of ionic liquid,the interaction between cation and anion can be adjusted.In order to find a stronger catalytic active site and enhance the contact between the active site and the reaction substance in the carrier.?2?Changes in the interaction between anions and cations have an impact on the physical properties of ionic liquids in confined areas.?3?There are mainly electrostatic force and hydrogen bond between anion and cation,while van der Waals force and Coulomb force mainly exist between ionic liquid and carrier.?4?The interaction between the ionic liquid and the pore wall makes the pore size of the body increasing,and the reactants easily enter the carrier.This helps to improve the catalytic activity of the catalyst and reduce the leaching rate.?2?Using density functional theory?DFT?method to study SiO₂ as the carrier,The CO₂ adsorption of[EMIM][Br],[EMIM][Cl],[EMIM][CH3COO]and[EMIM][PF6]in a confin range.The structure,charge distribution and interaction of CO₂ adsorption in confined ionic liquids and unconfined and are studied.The calculation results show that there is a strong interaction between the confined ionic liquid and CO₂.Under the confined environment,the interaction force between the anion and cation of the ionic liquid and CO₂under the influence of the carrier has been changed,resulting in a significant increase in the ability of the confined ionic liquid to adsorb CO₂.The results of the study show that in the confined environment,the adsorption capacity of hydrophobic ionic liquids to CO₂ is enhanced,and the adsorption capacity of hydrophilic ionic liquids to CO₂ is decreased.